Isolation and Structure Elucidation of New Secondary Metabolites from New Zealand Marine Red Algae

<p>The natural product analysis of New Zealand red algae has been neglected in recent years, and there is obvious scope for the chemical re-evaluation of New Zealand marine red algae. This study describes the isolation and structure elucidation of 12 new and eight known compounds from four different genera of red algae. To aid in this process, 34 red algae were screened in order to generate a digital HSQC spectra mask, a screening tool developed by the VUW Marine Natural Products group to identify extracts of interest for further analysis. All 34 algal extracts were screened using the HSQC mask and four extracts were identified as interesting and analysed in detail. Examination of extracts of the red algae Plocamium costatum and Ballia callitricha lead to the isolation of three known metabolites. Eleven new oxylipins, labillarides A to K, are reported from the alga Phacelocarpus labillardieri. Labillarides A to H are polyunsaturated alpha-pyrone macrocycles, all of which show similarities to the previously reported compounds isolated from southern Australian collections of the algae. Labillarides E to H are of particular interest as they represent the two diastereomeric pairs associated with variation at the C-3 and C-8 chiral centres. Labillarides I and J are related enol macrocycles while labillaride K is a furan-3-one oxylipin, all of which have biogenic significance to the macrocyclic alpha-pyrones. Labillarides A, B and I exhibit moderate cytotoxicity while labillaride C shows moderate antibacterial activity. A new nitrogenous bromophenol, colensolide A, was isolated from the alga Osmundaria colensoi along with five known bromophenols. The presence of nitrogen-containing sidechains in bromophenols is unusual but not unprecedented. The bicyclic nitrogenous moiety observed in colensolide A is proposed to be of histidine origin. Several of the known bromophenols exhibit antibacterial activity and one shows moderate cytotoxicity.</p>

Isolation and Structure Elucidation of New Secondary Metabolites from New Zealand Marine Red Algae

<p>The natural product analysis of New Zealand red algae has been neglected in recent years, and there is obvious scope for the chemical re-evaluation of New Zealand marine red algae. This study describes the isolation and structure elucidation of 12 new and eight known compounds from four different genera of red algae. To aid in this process, 34 red algae were screened in order to generate a digital HSQC spectra mask, a screening tool developed by the VUW Marine Natural Products group to identify extracts of interest for further analysis. All 34 algal extracts were screened using the HSQC mask and four extracts were identified as interesting and analysed in detail. Examination of extracts of the red algae Plocamium costatum and Ballia callitricha lead to the isolation of three known metabolites. Eleven new oxylipins, labillarides A to K, are reported from the alga Phacelocarpus labillardieri. Labillarides A to H are polyunsaturated alpha-pyrone macrocycles, all of which show similarities to the previously reported compounds isolated from southern Australian collections of the algae. Labillarides E to H are of particular interest as they represent the two diastereomeric pairs associated with variation at the C-3 and C-8 chiral centres. Labillarides I and J are related enol macrocycles while labillaride K is a furan-3-one oxylipin, all of which have biogenic significance to the macrocyclic alpha-pyrones. Labillarides A, B and I exhibit moderate cytotoxicity while labillaride C shows moderate antibacterial activity. A new nitrogenous bromophenol, colensolide A, was isolated from the alga Osmundaria colensoi along with five known bromophenols. The presence of nitrogen-containing sidechains in bromophenols is unusual but not unprecedented. The bicyclic nitrogenous moiety observed in colensolide A is proposed to be of histidine origin. Several of the known bromophenols exhibit antibacterial activity and one shows moderate cytotoxicity.</p>

Functional Feeds to Tackle Meagre (Argyrosomus regius) Stress: Physiological Responses under Acute Stressful Handling Conditions

Marine algae are recognised sources of bioactive compounds that have attracted great interest as nutritional supplements for aquaculture fish. Intensive rearing conditions often expose fish to husbandry-related stressors, rendering fish more susceptible to disease and reducing production yields. The present work evaluated the potential of two marine algae extracts (Fucus vesiculosus and Nannochloropsis gaditana) as nutritional supplements to mitigate stress effects in meagre (Argyrosomus regius) exposed to an acute handling stress (AS). A plant-based diet was used as a control, and three other diets were prepared, which were similar to the control diet but supplemented with 1% of each algal extract or a combination of the two extracts (0.5% each). The effects of supplemented diets on stress biomarkers, antioxidant enzyme activities, and immune response were analysed in fish exposed to AS after 4 weeks of feeding. Supplemented diets did not affect growth performance but the inclusion of F. vesiculosus promoted higher feed efficiency, as compared to the control group. Dietary algal extracts supplementation reduced plasma glucose levels, increased white blood cell counts, and reduced the expression of pro-inflammatory genes when compared with the control. N. gaditana supplementation led to a reduction in hepatic antioxidant enzyme activity and glutathione levels, while F. vesiculosus supplementation increased muscle glutathione reductase activity and reduced lipid peroxidation. These findings support the potential of algal extracts as nutraceuticals in aquafeeds to enhance the ability of fish to cope with husbandry-related stressful conditions and ultimately improve fish health and welfare.

Phytochemical, Antioxidant and Antimicrobial Activity of Biological Important Algae Hydrodictyon reticulatum L.

The recent research was directed to explore the phytochemical, antimicrobial and antioxidant activity of Hydrodictyon reticulatum L. The samples were then identified morphologically and anatomically. By using different solvents algal extracts were prepared. The phytochemical activity of algal samples were performed to determine the presence or absence of alkaloids, steroids, tannin, triterpenoids, saponin, terpenoids, quinine, coumarins, phlobatannins, phytosteroids and flavonoids. Two bacterial strains S. aureus and E. coli were used to determine the antibacterial activity of algal extracts. The greatest activity was appeared by the methanolic extract against the fungal strain S. aureus i.e. 12.5±0.088 mm, while the aqueous extract showed the maximum anti-bacterial activity that was 12.2±0.058 mm beside E. coli. These findings were relatively equivalent to the results of standard Amkasin that was normally used as antibiotic in the market. The results of antifungal movement was indicated greatest having the solvent (CH3)2CO separate i.e. 1.8±0.058 mm against A. niger. While methanol extricate indicated 2.35±0.058 mm against the strain F. solani. DPPH rummaging activity, TAA and TPC were performed to determine the action of reticulatum. In the event of DPPH the most extreme IC50 recorded was from the chloroform extricate. While in TPC methanol extricate indicated most extreme esteem 67.14±0.54 mm and in TAA ethanol showed greatest esteem i.e. 0.88±0.01 µg/L. These results demonstrated that the Hydrodictyon reticulatum had phytochemical, cancer prevention agent and antimicrobial potential and suggested for pharmaceutical use.

Sulfoquinovose metabolism in marine algae

This study aimed to survey algal model organisms, covering phylogenetically representative and ecologically relevant taxa. Reports about the occurrence of sulfonates (particularly sulfoquinovose, taurine, and isethionate) in marine algae are scarce, and their likely relevance in global biogeochemical cycles and ecosystem functioning is poorly known. Using both field-collected seaweeds from NW Scotland and cultured strains, a combination of enzyme assays, high-performance liquid chromatography and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry was used to detect key sulfonates in algal extracts. This was complemented by bioinformatics, mining the publicly available genome sequences of algal models. The results confirm the widespread presence of sulfonates and their biosynthetic pathways in macro- and microalgae. However, it is also clear that catabolic pathways, if present, must be different from those documented from the bacterial systems since no complete cluster of gene homologues of key genes could be detected in algal genomes.

Biological control of soil borne cucumber diseases using green marine macroalgae

Background In this study, the potential of extracts and powders of green seaweeds, Ulva fasciata, and Enteromorpha flexuosa was evaluated as biocontrol against the pathogenic soil-borne fungi, Macrophomina phaseolina and Fusarium solani, infecting cucumber plants in Egypt. The antifungal activity of the algal extracts was evaluated in vitro against the pathogens mycelial fungal growth using five organic solvents. Results Obtained results indicated that mycelial growth inhibition was noticed with F. solani in all algal extracts tested. In M. phaseolina, all algal extracts did not inhibit the fungal growth but affected microsclerotia formation (the main source of the second infection). In the case of F. solani, the highest reduction (68.6%) was noticed, while the chloroform extract of U. fasciata inhibited the radial growth of F. solani to 2.5 cm when E. flexuosa inhibited the radial growth to 4.3 cm as compared with the control (8.0 cm). The gas chromatography-mass spectrometry and the infrared spectroscopy analyses revealed that iron-monocarbonyl, cyclononasiloxane, and their functional groups, including amine, ether, etc., might play a core role in the anti-fungal activity of the seaweed extracts used. Conclusion This work concluded that the macroalgae species with many unique antifungal properties components had an inhibitory effect against soil-borne cucumber diseases. The antimicrobial activity might be explored in the future in numerous diverse applications in agriculture and plant disease control, revealing their actions to control some plant fungal pathogens.